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Home >> Mazda >> 2017 >> CX-5 Grand Select, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 145 (On-Board Diagnostic - Engine Control (2 Of 5)) >> DTC P0038; Pcm Ho2S Heater Control Circuit High Input >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2017 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA (MODE 2)/SNAPSHOT DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED
  • Have the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS (A/F sensor heater, HO2S heater related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
 Yes Perform repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 INSPECT HO2S CONNECTOR CONDITION
  • Switch the ignition off.
  • Disconnect the HO2S connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector and/or terminals, then go to Step 7.
No Go to the next step.
4 INSPECT PCM CONNECTOR CONDITION
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector and/or terminals, then go to Step 7.
No Go to the next step.
5 INSPECT HO2S HEATER CONTROL CIRCUIT FOR SHORT TO POWER SUPPLY
  • Verify that the HO2S and PCM connectors are disconnected.
  • Switch the ignition ON (engine off).
    NOTE:
    • Another DTC may be stored by the PCM detecting an open circuit.
  • Measure the voltage at the HO2S terminal D (wiring harness-side).
  • Is the voltage 0 V?
 Yes Go to the next step.
No Refer to the wiring diagram and verify whether or not there is a common connector between HO2S terminal D and PCM terminal 2C.
If there is a common connector:
  • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to power supply.
  • Repair or replace the malfunctioning part.

    If there is no common connector:

  • Repair or replace the wiring harness which has a short to power supply.

Go to Step 7.
6 INSPECT HO2S HEATER Yes Replace the HO2S, then go to the next step.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to the next step.
7 VERIFY DTC TROUBLESHOOTING COMPLETED Yes Repeat the inspection from Step 1.
Go to the next step.
No Go to the next step.
8 VERIFY AFTER REPAIR PROCEDURE Yes Go to the applicable DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.0, SKYACTIV-G 2.5)] .)
No DTC troubleshooting completed.
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